Portion of an adjustable forehead support dial for a respiratory mask



FIG. 1 is a front perspective view of a portion of an adjustable forehead support dial for a respiratory mask according to our design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof; and,

FIG. 4 is a side view thereof.

Where included, broken lines showing environment or structure are for illustrative purposes only and form no part of the claimed design. Where included, dotted lines represent the border between claimed and non-claimed subject matter and form no part of the claimed design. 

The ornamental design for a portion of an adjustable forehead support dial for a respiratory mask, as shown and described. 